Field of Invention
The present invention relates generally to detecting, locating and repairing signal leaks in a hybrid fiber-coax (HFC) network, and more particularly to a system and method of prioritizing the repair of such signal leaks.
Background Art
The advent of wireless Long Term Evolution (LTE) 4G technology has required the cable television industry to re-evaluate the signal leakage detection processes and to include detection of leaking QAM channel signals at frequencies at or near the LTE band. Since the 1980's, the FCC has defined monitoring requirements and allowable cumulative signal leakage limits for all cable television networks carrying channels in the aeronautical band. As a result of required compliance efforts, as well as good construction, management, and workmanship practices, cable networks have had relatively high signal integrity at the aeronautic frequencies. But, detection of signal leakage in the aeronautical band may have little correlation with signal leakage in the LTE band, and leak mitigation efforts in the aeronautical bands may not have a corresponding benefit in mitigating leaks in the LTE band. Until recently, technology that allowed cable network operators to detect and measure leaking QAM channels at or near LTE frequencies was not available. Thus, cable operators had minimal visibility of these higher frequency leaks. As a result, there are numerous leaks that exist at the LTE band. Generally, there may be an average of one LTE leak per cable plant mile. It is unrealistic to attempt to repair all such leaks.
With the existence of so many higher frequency leaks in the cable network, there is a need to have an intelligent method of prioritizing such leaks, in order to focus on those that are most likely to adversely affect the cable network (i.e., be “network affecting”) or an LTE network in the vicinity of the cable network (i.e., by way of egress). Egress of QAM signals from the cable network can adversely affect the LTE base transceiver station (BTS) performance by raising the BTS receiver noise floor and effectively decreasing the coverage area. Ingress of LTE signals (from BTS transmitters) entering the cable network through the leak can adversely affect the quality of signal transmission of the QAM channels downstream of the leak. Thus, from a quality of service and customer satisfaction perspective it is important to quickly react to repair these leaks.
Basing repair decisions solely upon the amplitude of the detected leak may not result in the most network affecting leaks being identified. The LTE signal strength at the leak location should also be considered. For example, a leak that is located relatively far from a LTE BTS transmitter, where the LTE level at the leak is very low or non-existent, should have a relatively low priority to repair. This is so because it is unlikely that egress from that distant leak location will affect the LTE BTS performance or that the LTE signal ingress will affect the quality of the QAM signals in the network. Comparing this to a leak of the same amplitude in close proximity to the LTE BTS, where the LTE signal strength is very high, the likelihood of both ingress and egress-related impairments is high. Therefore, this leak should have a relatively high priority.